Now I am confused...should the coop be dark or light?

My brother in law who is a veterinarian and also a farm owner told me that chickens need allot of light for egg production.
However, everything I have read states that the chicken likes dark nesting areas to lay. My coop is small so how do I manage this? The girls LOVE THEIR COOP but perhaps their nests need to be a be ....more private?
Any suggestions would be greatly appreciated!

What they mean by alot of light is Length of daylight, not necessarily wattage in the coop.

They lay best when they are exposed to 12 hrs give or take of "daylight". This can be artifically simulated with a lightbulb.

So as fall & winter approach, its starting to get dark earlier & earlier. You may consider leaving the light on in the coop beyond 6 or 7pm or starting earlier in the a.m. - you can use a timer for this if you like.